The fractional PID controllers tuned by genetic algorithms for expansion turbine in the cryogenic air separation process/PID kontroleri necelobrojnog reda podeseni genetskim algoritmima za upravljanje ekspanzione turbine u procesu separacije utecnjenog vazduha

• Published in: Hemijska industrija 2014-09, Vol.68 (5), p.519
• Main Authors: Bucanovic, Ljubisa J, Lazarevic, Mihailo P, Batalov, Srecko N
• Format: Article
• Language: English
• Subjects: Control equipment; Genetic algorithms; Properties; Turbines
• ISSN: 0367-598X
• DOI: 10.2298/HEMIND130717078B

This paper deals with the design of a new algorithm of PID control based on fractional calculus (FC) in production of technical gases, i.e. in a cryogenic air separation process. Production of low pressure liquid air was first introduced by P.L. Kapitsa and involved expansion in a gas turbine. For application in the synthesis of the control law, for the input temperature and flow of air to the expansion turbine, it is necessary to determine the appropriate differential equations of the cryogenic process of mixing of two gaseous airflows at different temperatures before entrance to the expansion turbine. Thereafter, the model is linearized and decoupled and consequently classical PID and fractional order [PI.sup.β][D.sup.α] controllers are taken to assess the quality of the proposed technique. A set of optimal parameters of these controllers are achieved through the genetic algorithm optimization procedure by minimizing a cost function. Our design method focuses on minimizing performance criterion which involves IAE, overshoot, as well as settling time. A time-domain simulation was used to identify the performance of [PI.sup.β][D.sup.α] controller with respect to a traditional optimized PID controller. Keywords: technical gases, cryogenic liquid, fractional PID control, FOPID optimal tuning, genetic algorithms. Ovaj rad se bavi realizacijom jednog novog algoritma PID upravljanja zasnovanog na racunu necelobrojnog reda (fractional calculus) u proizvodnji tehnickih gasova, odnosno u procesu separacije utecnjenog vazduha. Proizvodnja utecnjenog vazduha niskog pritiska je po prvi put bila uvedena od strane Kapice gde se ekspanzija odvijala u gasnoj turbini.Za primenu u sintezi upravljanja ulazne temperature i protoka vazduha u ekspanzionoj turbini, potrebno je odrediti odgovarajuce diferencijalne jednacine kriogenog procesa mesanja dva gasa na razlicitim temperaturama na ulazu u ekspanzionu turbinu. Pri tome, odgovarajuci model je linearizovan i dekuplovan gde su primenjeni istovremeno klasicni PID kao i [PI.sup.β][D.sup.α] kontroleri necelobrojnog reda da bi se procenio kvalitet predlozenog novog upravljanja datim procesom. Skup optimalnih parametara datih kontrolera se postize primenom optimizacione procedure bazirane na genetskim algoritmima minimizovanjem odgovarajuceg kriterijuma optimalnosti. Nas metod se fokusira u okviru kriterijuma optimalnosti na smanjenje preskoka, vreme smirenja i minimizaciju integralne greske. Simulacije sprovedene u vremenskom do